Set into the ground of the chancel area, the holiest and most restricted part of a Cistercian church, lies a tapering graveslab nearly two metres long. Across its upper portion, someone in 1828 had an inscription cut directly over a medieval cross, announcing that the tomb was the property of one Patrick Tool, placed there by a Michael Gallane for Tool "& posterity". The medieval carving beneath it predates that claim by several centuries.

Corcomroe is a Cistercian abbey, part of an order of monks founded in twelfth-century Burgundy who favoured plain architecture and remote locations; the Burren's limestone landscape suited both requirements well. The graveslab itself is a careful piece of work. The cross is carved in low relief with fleur-de-lis terminals, the decorative three-petalled flourish borrowed from heraldry, finishing each of the three upper arms and the base of the shaft. At the centre of the cross head there is a small square depression, roughly three centimetres square, possibly a socket for a now-missing inlay or pin. The edges of the slab are chamfered on all four sides, meaning they are cut at a slight angle rather than squared off, which is a common finishing technique on medieval funerary stonework. A crack runs across the stone about a third of the way up from the foot. The 1828 inscription does not replace or erase the medieval cross so much as sit across it, the newer lettering superimposed on the older geometry in a way that makes both legible at once, if you look carefully enough.